The invention relates in particular to a method and a system that are used to produce microstructured components by means of photolithography. Microstructured components are inter alia integrated circuits, semiconductor chips or micro-electromechanical systems (MEMS). A substrate (also known as a “wafer”) is used for the photolithography method, said substrate being coated with a photoresist (also known as a “resist”). The coated substrate is subsequently exposed by means of a mask, wherein the physical and/or chemical characteristics of the photoresist at least in part change owing to the exposure.
The photoresist is applied to the substrate typically in a layer. It is extremely important that the applied resist layer is free of irregularities or particles. It is therefore known from the prior art that the coating is applied to the substrate by means of a rotation method (“spin coating”) so that said coating is distributed as equally as possible on the surface of the substrate.
However, it has been proven that a bead in the coating can occur on the edge of the upper side of the substrate owing to the rotation method since the coating is pushed radially outwards as a result of the centrifugal force when rotating the substrate.
In the prior art, this coating bead is either removed manually or is removed by means of a solvent which however leads to an increased expenditure when producing the coated substrate or can lead to impurities.
In addition, a method for coating a substrate is known from KR 2010/0078033 A, wherein the coating material at the upper side of the substrate is exposed to a gas flow from an outflow device allocated to the upper side. The gas flow generates a pressure on the coating material to prevent the formation of a bead and to push away the coating material of a bead already formed. The gas flow generated in this way directly impinges on the upper side.
The photoresist represents the coating material in the case of the above mentioned specific field of application. In the case of other field of applications, it is possible however to use another coating material, by way of example a fluid material such as an aerogel. It is also possible to use an adhesive, an asphalt or clay as coating materials in their respective fields of application, said coating materials being applied to the substrate by means of a rotation method. It is also possible to apply dry materials in a rotation method so that said dry materials can also be used as coating materials.
In general, in the case of coating materials that are applied by means of a rotation method, it is possible that the coating material forms a bead on the edge of the respective substrate, which is undesired.